31856421 has 12 divisors (see below), whose sum is σ = 43493568. Its totient is φ = 20740104.

The previous prime is 31856417. The next prime is 31856431. The reversal of 31856421 is 12465813.

It is not a de Polignac number, because 31856421 - 2² = 31856417 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31856411) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2676 + ... + 8418.

It is an arithmetic number, because the mean of its divisors is an integer number (3624464).

Almost surely, 2^31856421 is an apocalyptic number.

It is an amenable number.

31856421 is a deficient number, since it is larger than the sum of its proper divisors (11637147).

31856421 is an equidigital number, since it uses as much as digits as its factorization.

31856421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5832 (or 5789 counting only the distinct ones).

The product of its digits is 5760, while the sum is 30.

The square root of 31856421 is about 5644.1492715909. The cubic root of 31856421 is about 317.0046704258.

The spelling of 31856421 in words is "thirty-one million, eight hundred fifty-six thousand, four hundred twenty-one".